1. Field of the Invention
The present invention relates to an optical multiplexer/demultiplexer module and prism using the same that are applied to an optical communication system and to the optical measurement field.
2. Description of the Related Art
Recently, with the rapid spread of broadband, study and research in order to increase the speed of optical transmission systems is actively being pursued. Optical multiplexer/demultiplexer modules are used in this kind of optical transmission system. The technology for this kind of optical multiplexer/demultiplexer module is known, such as disclosed in patent document 1. This conventional optical multiplexer/demultiplexer module has construction in which a filter is arranged between two collimating lenses. The filter reflects the λ1 signal light of the collimated light from one collimating lens, and lets the λ2 signal light of the collimated light from the other collimating lens pass through. The λ1 signal light that was reflected by the filter and the λ2 signal light that passed through the filter are optically coupled with an optic fiber by way of the collimating lenses.    [Patent Document 1] Japanese patent Laid-open publication No. 2003-315611
However, in the conventional technology disclosed in patent document 1, in the case where the filter tilts at an angle θ due to change in the ambient temperature, the optical path of the transmitted light does not change, however, since the angle of the reflected light is 2θ, that reflected light is not optically coupled with the optic fiber by way of the collimating lenses.